PSI 1.5 loads and works perfectly on windows 7 home premium 64 bit.
Removed it to load version PSI 2. PSI 2 loads but crashes immediately and refuses to finalize. Had to remove it and reload 1.5 which again works perfectly.

I don't now why but this is the real result. I'll stay with 1.5 for while longer.

Hello.
It is usual for psi to remove the previous version ( with permission), if you allow it to do so. Did you clear temporary files/browser cache before install ? Perhaps try another browser for the install? Just a couple of suggestions.....regards,

The original 1.5 was removed with the add/remove programs function on windows
Then the new 2 version was installed by its install program. ditto when 2.0 was removed and 1.5 reinstalled. Browser was Firefox and it is the only one I will use!